If you're really tethering (using the Blackberry modem driver) they know you are tethering. With Sharkmodem you could be using the browser or something like Verichat. I have used it successfully since it was released, and I have never been charged (on Cingular). It's a cool product. There is a small app for the Blackberry and one for the PC, and together they act like a proxy server. The one downside is that you have to configure your PC apps (browser, email client, etc) to connect to the internet through a proxy server. But, the app works very well.

SharkModem is a breakthrough anyway because it lets pratically ANY BlackBerry (7XXX) become tetherable on almost any carrier. Even from a lowly BlackBerry 7230 or 7510. This is an achievement in itself anyway; these were never designed to be tethered!...

If you can tether natively using Verizon BroadBandAccess, that's better than using SharkModem....

However, if the carrier doesn't let you tether at all (i.e. Nextel!), then SharkModem saves the day -- it makes the impossible into possible...

Also, for BES users, it also allows tethering data over your BES to access your Intranet using your preexisting encrypted BES connection as the makeshift VPN. (without needing to configure a VPN, while still remaining as secure as a VPN)

SharkModem essentially borrows the existing BlackBerry's email/web connection. So if you're able to use the web browser on the BlackBerry. Whatever you are able to access in the BlackBerry Browser, now becomes accessible via Internet Explorer on your laptop. Essentially, the BlackBerry behaves as the proxy server for your laptop. That's how SharkModem really works. Very clever programming, and I predicted it was possible, long before SharkModem existed...